Laboratory setup for rapid in situ powder X-ray diffraction elucidating Ni particle formation in supercritical methanol

Abstract

The design and function of a custom-made Soller slit for a laboratory 2D area detector is presented through a series of demonstration images and an in situ experiment following the formation of nickel particles in supercritical methanol. The in situ experiment is performed in a capillary sample environment, modified for a laboratory scale Rigaku Smartlab diffractometer, and with a temperature range of 300-1050 K. The formation of nickel particles was followed successfully using laboratory in situ X-ray powder diffraction with a time resolution in the order of 27 s. Observations from the area detector images showed the appearance of three distinct phases during the reaction: Ni3(NO3)2(OH)4, NiO, and Ni. The images were linearly integrated and analyzed using Rietveld refinement. A reaction mechanism is proposed based on an evaluation of the weight fractions and scattering factors as a function of reaction time.